A member of the Home Guard demonstrates a rifle equipped to fire an anti-tank grenade, Dorking, 3 August 1942.

The No. 68 was an early form of shaped charge grenade, and has some claim to have been the first High Explosive, Anti Tank (HEAT) device in use. The design of the warhead was simple and was capable of penetrating 52mm (2 inches) of armour in 1940.[1]

The fuze of the grenade was armed by removing a pin in the tail which prevented the firing pin from flying forward. The grenade was launched from a rifle cup. The simple fins gave it some stability in the air and, provided the grenade hit the target at the proper angle (90 degrees), the charge would be effective. Detonation occurred on impact, when a striker in the tail of the grenade overcame the resistance of a creep spring and was thrown forward into a stab detonator.